C2.2 Neural Signalling

Positive correlation

A correlation where as one variable increases, the other also increases, or as one decreases so does the other. Both variables move in the same direction.

Negative Correlation

as one variable increases, the other decreases

Coefficient of Determination (R2)

The fraction of the variation in the values of y that is accounted for by the least-squares regression line of y on x.

Presynaptic Membrane

the membrane of a terminal button that lies adjacent to the postsynaptic membrane and through which the neurotransmitter is released

Synaptic Cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

Postsynaptic membrane

the cell membrane opposite the terminal button in a synapse; the membrane of the cell that receives the message

Neurotransmitter

chemical messengers that cross the synaptic gaps between neurons

Acetylcholine

A neurotransmitter that enables learning and memory and also triggers muscle contraction

Neuron

a nerve cell; the basic building block of the nervous system

Nerve fiber

long axon

dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

Axon terminal

The endpoint of a neuron where neurotransmitters are stored

Sensory neuron

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

Interneuron

a neuron that carries nerve impulses from one neuron to another

Sensory Neuron

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

Resting Potential

The difference in electric charge between the inside and outside of a neuron's cell membrane

Sodium-Potassium Pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Nerve Impulse

the message carried by a neuron

Action Potential

a neural impulse; a brief electrical charge that travels down an axon

Myelin

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Myelinated axons

axons covered with myelin sheaths

Non-myelinated axons

still protected by Schwann cells

slower conduction velocities

pain sensation

Correlation

A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

Depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Repolarization

Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

Hyperpolarization

The movement of the membrane potential of a cell away from rest potential in a more negative direction.

Threshold Potential

The minimum membrane potential that must be reached in order for an action potential to be generated.

Voltage-Gated Channels

open and close in response to changes in membrane potential

Local Currents

Currents in cytoplasm of neurone, caused by depolarisation due to sodium ions flooding back into neurone

Oscilloscope

A piece of test equipment used to view and measure a variety of different waveforms.

Oscilloscope Trace

The wave pattern seen on the screen of an oscilloscope.

Saltatory Conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

Myelin Sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Nodes of Ranvier

gaps in the myelin sheath

Exogenous Chemicals

originating outside of the body (drugs)

Neonicotinoids

a systemic agricultural insecticide resembling nicotine.

Pesticides

Chemicals used on plants that do not harm the plants, but kill pests and have negative repercussions on other species who ingest the chemicals.

Cocaine

a powerful and addictive stimulant, derived from the coca plant, producing temporarily increased alertness and euphoria

Dopamine Transporters

Molecules in the presynaptic membrane of dopaminergic neurons that attract dopamine molecules in the synaptic cleft and deposit them back inside the neuron.

Inhibitory Neurotransmitters

inhibit the next cell from firing

Excitatory Neurotransmitters

excite the next cell into firing

Nociceptors

sensory receptors that enable the perception of pain in response to potentially harmful stimuli

Consciousness

our awareness of ourselves and our environment

Emergent Properties

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.